Video surveillance systems apply image processing to enhance or obscure visual information as necessary. It is useful to be able to define the extents within which image processing operations should take place; for example moving region detection and object tracking software may define the bounding box of a suspicious object and use it to direct enhancement processing to the appropriate area of the image. Alternatively many surveillance systems require selected regions to be marked as private. A private region is an area that is not output from the camera and may not necessarily be viewed or recorded. Example areas requiring privacy might include changing rooms in shops or the contents of computer screens. These regions should be obscured.
Privacy may be implemented by masking off areas that should not be viewed either with mechanical obstructions blocking the line of sight of the camera or by electronically blanking the video signal at appropriate times, as discussed in U.S. Pat. No. 6,049,281, which is hereby incorporated by reference. It is however, much more difficult to implement privacy regions in surveillance systems that use standard pan-tilt-zoom (PTZ) cameras. The difficulties arise from the need to block out a region of captured video, where that region must stay fixed with respect to the world independent of the state of pan, tilt, or zoom of the camera. Many implementations rely on a mechanical measurement of the orientation of the camera and under rapid movement the measurement may lag the movement of the camera, which results in the private regions becoming momentarily visible. For example, U.S. Pat. No. 6,509,926, which hereby is incorporated by reference, discusses a unit for generating the azimuth and elevation angles of a camera and lens.
A new class of camera replaces the mechanical PTZ mechanisms by a wide-angle optical system and image processing (as discussed in U.S. Provisional Application 60/467,588, which is hereby incorporated by reference). This type of camera monitors a wide field of view and selects regions from it to transmit to a base station; in this way it emulates the behavior of a mechanical PTZ camera. The wide-angle optics introduces distortion into the captured image and processing algorithms are used to correct the distortion and convert it to a view that has a similar view as a mechanical PTZ camera. This type of camera may be used to improve the processing of selected regions because a wide field is always captured by the camera and there is no need for mechanical measurement.
There is a need in the art for a way to provide obscured regions of images or video, whether in a still camera or a PTZ camera.
Image Processing of Regions in a Wide Angle Video Camera
In one example embodiment, the present innovations include a system and method for capturing images and providing a privacy region (or other defined region for processing). In preferred embodiments, the present innovations include a camera for capturing wide angle images, correcting those images, allowing an operator or other means to select a region for processing (preferably for privacy obfuscation, but potentially for other processing such as object tracking or alarms), and displaying the image or video with the privacy regions obscured. The present innovations can be performed in a number of varying process flows, including but not limited to correction before or after the privacy region is defined, and correction before or after the privacy region is merged with the rest of the image or video. Further, preferred embodiments allow other processing (such as object tracking or alarms, for example) to be performed at varying points in the process, as needed in a given implementation. These and other innovative aspects of the present inventions are described more fully below.